1. Field of the Invention
The invention relates to an improved stent and stent/graft deployment catheter. More particularly, the invention relates to a stent which is capable of being loaded into the delivery sheath of a stent/graft deployment catheter without suffering any structural damage and which is uniformly radially compressed during packing.
2. Description of the Prior Art
An abdominal aortic aneurysm (AAA) is a sac caused by an abnormal dilatation of the wall of the aorta as it passes through the abdomen. The aorta is the main artery of the body, supplying blood to all organs and parts of the body except the lungs. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen, and finally divides into the iliac arteries which supply blood to the pelvis and lower extremities.
The AAA ordinarily occurs in the portion of the aorta below the kidneys. When left untreated, the aneurysm will eventually cause the sac to rupture with ensuing fatal hemorrhaging in a very short time. The repair of abdominal aortic aneurysms has typically required major abdominal surgery in which the diseased and aneurysmal segment of the aorta is bridged with a prosthetic device, such as a synthetic graft.
As with all major surgeries, there are many disadvantages to the above mentioned surgical technique, the foremost of which is the high mortality and morbidity rate associated with surgical intervention of this magnitude. Other disadvantages of conventional surgical repair include the extensive recovery period associated with such surgery; difficulties in suturing the graft to the aorta; the unsuitability of the surgery for many patients, particularly older patients exhibiting comorbid conditions; and the problems associated with performing the surgical procedure on an emergency basis after the aneurysm has already ruptured.
In view of the above mentioned disadvantages of conventional surgical repair techniques, techniques have been developed for repairing AAAs by intraluminally delivering an aortic graft to the aneurysm site through the use of a catheter based delivery system, and securing the graft within the aorta using an expandable stent. Since the first documented clinical application of this technique was reported by Parodi et al. in the Annals of Vascular Surgery, Volume 5, pages 491-499 (1991), the technique has gained more widespread recognition and is being used more commonly.
Problems have been encountered accurately deploying the stent/graft. These problems are partially due to the method of packing the stent/graft into the delivery sheath of the deployment catheter. Currently, the stent/graft is manually radially compressed and pushed into the delivery sheath. This stent/graft compress and push method is problematic for a number of reasons. First, this process often leads to breakage of the stent struts. A stent with broken struts may not expand as designed, and as a result, will not properly bridge the AAA upon deployment. Second, this compress and push method of stent/graft packing produces a non-uniformly compressed stent. Unless all of the stent cells are equally compressed the stent/graft may not expand as designed upon exposure to the patient""s blood, and as a result, the stent/graft will not adequately bridge the AAA. Another drawback of the present compress and push method of stent/graft packing is that it is very time consuming and difficult, and therefore, it is inappropriate for large scale production.
Therefore, the need exists for an improved method for inserting a stent/graft into the delivery sheath of a deployment catheter. Furthermore, the need exists for an improved stent and a stent/graft deployment catheter which is capable of being loaded with a stent/graft using the improved stent/graft packing method.
Accordingly, it is an object of the invention to produce a method for inserting a stent/graft which overcomes the deficiencies of the prior art compress and push packing method.
It is another object of the invention to produce a stent/graft deployment catheter capable of pulling a uniformly compressed stent/graft into its delivery sheath without damaging the stent/graft.
It is a further object of the invention to produce a stent with V hooks capable of being pulled into the delivery sheath of the stent/graft deployment catheter.
The invention is a method for inserting an improved stent into the delivery sheath of an improved stent/graft deployment catheter. The stent has V hooks on its proximal end which are positively engageable by projections attached to a stent/graft deployment catheter plunger. The proximal end of the stent is manually squeezed over the V hooks such that the V hooks engage the projections. The catheter is passed through the center of a funnel. While maintaining pressure on the stent and the V hooks, the plunger is withdrawn so as to pull the stent into the delivery sheath through the center of the funnel. The funnel guides the stent into the delivery sheath and uniformly compresses the stent as it approaches the delivery sheath.
To the accomplishment of the above and related objects the invention may be embodied in the form illustrated in the accompanying drawings. Attention is called to the fact, however, that the drawings are illustrative only. Variations are contemplated as being part of the invention, limited only by the scope of the claims.